Second Data Release of the COSMOS Lyman-alpha Mapping and Tomographic Observation: The First 3D Maps of the Large-Scale Cosmic Web at 2.05<z<2.55

We present the second data release of the COSMOS Lyman-Alpha Mapping And Tomography Observations (CLAMATO) Survey conducted with the LRIS spectrograph on the Keck-I telescope. This project used \lyaf absorption in the spectra of faint star forming galaxies and quasars at z~ 2-3 to trace neutral hydrogen in the intergalactic medium. In particular, we use 377 objects over a footprint of ~0.2 deg^2 to reconstruct the absorption field at 2.05 < z < 2.55. We apply a Wiener filtering technique to the observed data to reconstruct three dimensional maps of the field over a volume of 4.1 x 10^5 (h^{-1} Mpc)^3. In addition to the filtered flux maps, for the first time we infer the underlying dark matter field through a forward modelling framework from a joint likelihood of galaxy and \lyaf data, finding clear examples of cosmic voids, filaments, and nodes. This work constitutes the highest redshift identification of the large scale cosmic web. In addition to traditional figures, we present a number of interactive three dimensional models to allow exploration of the data and qualitative comparisons to known galaxy surveys. We find that our inferred over-densities are consistent with those found from galaxy fields. We will make all our reduced spectra, extracted Lyman-alpha forest pixel data, and reconstructed tomographic maps available publicly upon publication.